Photographic developer



Patented Feb. 12, 1946 I UNITED. STATE S PATENT oFF ca rno'roenarnrc DEVELOPER Frederic R.. Bean, Rochester, N. Y., assignor to Eastman Kodak" Company, Rochester, N. Y., a

corporation of New Jersey No Drawing. Application December a, 194

' Serial No. 513,487

"sciaims. (01.95 88) CHzOHKCl-IOH) 4.CH2OH+NaOH- air-stable, moisture-resistant alkali for use in.

photographic developers. Another object is to provide an alkali which will give, in photographic developers, approximately the same alkalinity and results as sodium hydroxide. Another object is to provide a stable, non-caking, ready-mixed, dry developer powder. Still another object is to provide a stable, non-caking, ready-mixed, single dry developer powder. Other objects will hereinafter appear. Y

Alkaline'developers have been known and used for many years. These developers usually contain developingagentaa so-called preservative, such as sodium sulflte, and an alkali. One of the oldest and most useful alkalies used in photographic developers is sodium hydroxide, otherwise known as caustic soda. The degree of alkalinity which it confers upon a developer has been found to be most suitable for certain purposes. However, sodium hydroxide is deliquescent and corrosive, and for this reason is difficult to handle, weigh, store and package. Moreover, when used in ready-mixed, packaged developer powders, which, because of their convenience and uniformit'y, are very popular among both amateur and professional photographers, sodium hydrox- CH2OH.(CHOH) 4.CH2ON8.+H2O

Greater than molecular quantities of mannitol or sorbitol may be used in the reaction mixture, conferring even higher moisture resistance to the resulting compound.

When sorbitol was used in place of mannitol, in the same quantity and under practically the same conditions, a similar reaction occurred, giving a product closely resembling that obtained with mannitol.

pH measurements indicated that these products were completely hydrolyzed when dissolved in water. When molecularly equivalent quantities of sodium hydroxide and of s ium mannitoxide i were dissolved separately in water, they gave the same-pH or alkalinity.

' single-powder developers, since they do not react upon the other dry chemicals presentin the ide is apt to cause caking, discolorationand deterioration of the powder. This renders impracticable the preparation of asingle-powder developer. containing sodium hydroxide.

I have discovered that a monosodium deriva- .tive of a hexahydric alcohol, such as mannitol or sorbitol, is a suitable substance for'use in photographic developers in which it is desired to have the alkaline properties of sodium hydroxide without its undesirable properties. As an example of a method by which such a sodium derivative may be prepared, I give the following:

' Example, 1

Sodium mannitoxide and the corresponding monosodium derivative of sorbitol are stable, moisture resistant compounds which can be weighed, stored and handled with ease. They can be used in place of sodium hydroxide, in molecularly equivalent proportions, in all .photographic developer formulae in which sodium hydroxide'is used. with the same photographic results. Moreover, they can be used to prepare powder.

As an example of a single-powder developer containing sodium mannitoxide, I give the following. It will be understood that this example is illustrative only, and that'sodium mannitoxide,

orthe equivalent monosodium derivative of another hexahydric alcohol, such, for instance, as

' sorbitol, may be substituted for the molecularly To 45.5 grams offmannitol, heated to about weeks- The yield was about 51 grams, the theo-' retical amount according to the equation:

equivalent amount of sodium hydroxide in any photographic silver-image developer formula, whether the developer be in dry form or in solu tion. I

ErampleZ Grams Sodium s fl 4 11.25 Hydroquinone 5.62 Sodium mannitoxide s 30.00 Potassium bromide 3.75 Potassium metabisulflte 5.00

For 'use dissolve in 250 cc. of water.

This developer has all ingredients mixed intimately together in a single containerand remains stable in dry form, without discoloration. When a single powder was prepared, containing the same ingredients in the same proportions, ex-

cept that 6.68 g. of'sodium hydroxide was'substituted for the 30 g. of sodium mannitoxide, discoloration and deterioration occurred immediately.

If a buflered solution is desired from a singlepowder developer in which sodium mannitoxide or other mono-sodium derivative of a hexahydric alcohol is used. boric acid can be added in suf- .ficient quantity to get the bufier eflect.

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

'1. A photographic developer containing a developing agent and'a monosodium derivative of a hexahydric alcohol as an alkali.

2. A photographic developer containing a developing agent and a monosodiuni derivative of mannitolasanalkali.

3. A photographic developer containing a developing agent and a monosodium derivative of sorbitol'as'an alkali. t

4. A photographic developer, in dry form, containing a developing agent and a monosodium derivative of a hexahydric alcohol'as an alkali.

- 5. A photographic developer in theform ot a singe dry powder, containing .a developing agent and a monosodium derivative of a hexahydric alcohol as an alkali.

: i FREDERIC R. BEAN. 

